Costs associated with energy use by streetlights or parking lot lights can be a significant portion of a city budget. For example, in some cases costs associated with powering such lights can represent up to 10% of a city's operating budget. One way of minimizing energy use in street lights is to equip the lights with an ambient light sensor that causes each light to individually be fully powered on each evening when the sensed ambient light drops to a particular level. Similarly, the sensor may sense increasing ambient light in the morning as the sun rises, and may cause the light to be completely powered off at that time.